xuefuz commented on a change in pull request #8458: [FLINK-12452][table][hive]
alterTable() should ensure existing base table and the new one are of the same
type
URL: https://github.com/apache/flink/pull/8458#discussion_r284477042
##########
File path:
flink-connectors/flink-connector-hive/src/main/java/org/apache/flink/table/catalog/hive/HiveCatalogBase.java
##########
@@ -318,13 +320,44 @@ public void alterTable(ObjectPath tablePath,
CatalogBaseTable newCatalogTable, b
throw new
TableNotExistException(catalogName, tablePath);
}
} else {
- // TODO: [FLINK-12452] alterTable() in all
catalogs should ensure existing base table and the new one are of the same type
+ Table oldTable = getHiveTable(tablePath);
+ TableType oldTableType =
TableType.valueOf(oldTable.getTableType());
+
+ // Flink cannot alter existing Hive tables in
types that Flink cannot create for now,
+ // including EXTERNAL_TABLE, INDEX_TABLE and
MATERIALZED_VIEW.
+ // Note that though Flink cannot create them,
it's able to read most parts of their metadata,
+ // like schema and properties, thru existing
mechanism, but not their unique metadata.
+ // Also note that add capability of creating
EXTERNAL_TABLE should be fairly easy to do, e.g. with a table property
+ // "table_type=external", we just haven't done
it yet.
+ // INDEX_TABLE and MATERIALZED_VIEW need more
research.
+
+ if (oldTableType == TableType.EXTERNAL_TABLE
Review comment:
Instead of listing types that we don't support, it's probably better to
check if the type is what we do support.
Also event though Flink is not able to create external table yet, that's
probably due to the limitation of the DLL and I don't see why we should
disallow user to modify it.
It seems okay if we say we don't support other types yet.
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